Electronics Forum | Sat Jun 15 07:26:12 EDT 2002 | Daan Terstegge
A good PDF-file about tombstoning, written by Plexus, is accessible from http://www.xs4all.nl/~tersted/PDF_files/Plexus/tombstoning.pdf Daan Terstegge http://www.smtinfo.net
Electronics Forum | Wed Jun 12 03:26:03 EDT 2002 | edahi
We are currently having gross tombstoning with 0402 capacitors. We are using HiPb Solder Paste mounted on Laminate substrates. We are assembling Flip Chip BGA's. Temp @ Reflow is around 230-240 C to meet the thermal requirements for both die bump
Electronics Forum | Wed Jun 12 10:42:06 EDT 2002 | stepheno
Check your land patterns. I believe someone once made a typo on specs for land pattern spacing and the specs are still being used by some people. I worked for a CM that had a customer that spaced the pads for 0402's too far apart. It was the only
Electronics Forum | Wed Jun 12 18:04:47 EDT 2002 | stownsend
Is this a new problem on an old product, or is this a first run? If this is a new problem on an old product, you may want to check the paste process. If the paste is not even across both pads or is offset a bit, the parts will pop up. If this is a f
Electronics Forum | Fri Jun 14 14:32:05 EDT 2002 | davef
There is no real reason why you shouldn�t use your current paste. Paste for printing usually is a coarser mesh than paste for dispensing. Dispensing paste is more expensive, because of the mesh and the packaging, but that doesn�t matter now. Compa
Electronics Forum | Sat Jun 15 22:39:05 EDT 2002 | edahi
well we can't paste the flip chip on its substrate because we are using flux...because this bare die yet...and the surface of the die flipped might be contaminated...also after chip attach and reflow the die is to be underfilled and if the die is pas
Electronics Forum | Mon Jun 17 21:18:24 EDT 2002 | davef
I don't understand "well we can't paste the flip chip on its substrate because we are using flux". There is flux in paste. What's the difference? If you use solder paste, there will be more room for underfill, as compared to flux only. Some peopl
Electronics Forum | Wed Jun 12 08:24:03 EDT 2002 | davef
Tough. 0402 capacitors are more prone to tomb stoning than resistors. Tailor your process to the 0402 and let the other stuff fall where it falls. Search the fine SMTnet archives for discussion on tomb stoning. Consider: * Changing paste. * Apply
Electronics Forum | Thu Jun 13 06:08:57 EDT 2002 | edahi
guys thanks for the suggestions... DaveF, *Changing paste EricD: Yes we are considering that as a point. Because I believe the paste we are using are in syringe packaged and designed for dispensing. We are using an Indium SMQ75 paste and current
Electronics Forum | Thu Jun 13 11:27:25 EDT 2002 | davef
>*Changing paste >EricD: Yes we are considering that as a point. Because I believe the paste we are using are in syringe packaged and designed for dispensing. We are using an Indium SMQ75 paste and current application naturally is stencil printing.
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